A technique in which the acoustic characteristics of a speaker or a listening room are measured using a microphone and an audio signal is equalized on the basis of the results of the measurement has been put into practical use, and a technique for enhancing the accuracy of the measurement using the microphone has also been proposed (for example, refer to Patent Document 1). FIG. 1 is an external view showing a microphone device 100 having been used conventionally for this measurement. This microphone device 100 has a housing being composed of a disc-shaped base section 101 and a neck 102 provided upright at the center of this base section 101. At the top of the neck 102, an opening section 102A is provided, and inside the neck 102, a microphone unit 103 is incorporated toward the opening section 102A. In the above-mentioned measurement, the microphone device 100 is placed at a listening point, test sound is emitted from the speaker, and the test sound picked up by the microphone device 100 is analyzed to determine the acoustic characteristics of the speaker and the listening room.
Furthermore, as shown in FIG. 2, a technique wherein a microphone base 110 having three concave sections 111 is placed at a listening point, the microphone device 100 is mounted sequentially in the three concave sections 111, and test sound is picked up sequentially to measure the acoustic characteristics of the listening room three-dimensionally has also been put into practical use.